The composition and mutagenicity of compounds generated during the pyrolysis of solid fuels will be studied under well-defined experimental conditions in order to nominate compounds for more detailed biological studies and to develop chemical pathways for the formation of the compounds of greatest concern. Selected coals, woods, and model compounds representing moieties commonly found in coal and wood will be studied in either a flow apparatus or bed systems operated over temperature ranges and times encountered in common combustor types. The products will be analyzed, in collaboration with the core laboratory in Analytical Chemistry, to separate out major categories of substituted, unsubstituted, polar, and nitrogen-containing compounds for bioassay. The subgroups showing the greatest biological activity will be subjected to more detailed chemical analyses to identify the major mutagens. The chemical pathways leading to these compounds will be evaluated using frontier molecular orbital theory and by selected experiments with model compounds. The focus of the study will be on oxygen and nitrogen compounds, prevalent in the products of incomplete combustion of coal and wood and known to cause mutation of bacteria with or without enzymatic activation.